Until can be used as a subordinate conjunction (subordinate clauses follow until) and a preposition (noun/noun phrase/gerund/to infinite follows it.)
What is the grammar of these sentences?
Example 1: We will wait here until called. (called is a past participle) (until calling is okay as 'calling' is a gerund. 'until the call' is okay as well.)
Example 2: You are innocent until proven guilty. (guilty is an adjective. Proven is an adjective/past participle)
PS: If 'called' is a short form accepted by English grammar for 'we are called" then it is very confusing. Also, it doesn't make sense why then Grammar books say that subordinate conjunctions are followed by dependent clauses.